A typical flash memory device may comprise a memory array that includes a large number of non-volatile memory cells arranged in row and column fashion. In recent years, vertical memory, such as three-dimensional (3D) memory has been developed. A 3D flash memory (e.g., 3D NAND memory array) device may include a plurality of strings of charge storage devices (memory cells) stacked over one another. Each group of the plurality of strings may share a plurality of access lines, known as wordlines (WLs). Each of the plurality of access lines may couple (e.g., electrically connect via provided contacts) the charge storage devices (memory cells) corresponding to a respective tier of each string.
In a 3D memory device fabrication, the wordline contacts may be formed simultaneously with a single etch even though the contact landings may be at different latitude. However, it may be challenging to ensure during the etch process that the formed contact stops on a designated wordline, without leaking to another wordline (e.g., by punching through the designated wordline or leaking to the wordline underneath) and thus creating an undesired short circuit.